Dressing up.

What would potato salad be without mayonnaise? Or fish without tartar sauce? Or Chinese food without soy sauce?

In many cases, a lot less salty or fatty.

Don't get us wrong. Condiments are magical, as anyone who's ever added fine mustard to a marinade or a touch of soy sauce at the end of a soup's long simmer can tell you.

The trick is figuring out how to get the most condiment for the least fat or salt.

Mayo Culpa

If you haven't shopped for a low- or no-fat mayo lately, are you in for a treat.

Among the no-fats (less than a half-gram of fat per tablespoon, actually), Smart Beat Fat Free tasted the most like full-fat mayos, which have 11 to 12 grams of fat.

Smart Beat and the others have replaced mayo's oil with safe thickeners and emulsifiers like cellulose gum, modified food starch, and xanthan gum.

(Kraft Free resorts to artificial colors like Yellow 6 and Blue 1; Smart Beat sticks with paprika and beta-carotene.)

The no-fatties are fine if you're looking for something to slap on a sandwich. But the tuna and potato salad connoisseurs among us found them lacking a little "oomph."

If you agree, try Hellmann's Reduced Fat (west of the Rockies the brand is called Best Foods). It replaces (discontinued) Hellmann's Light. And at three grams of fat per tablespoon (vs. Light's five), what a nice replacement it is.

Mayos that are made with canola or safflower oil aren't nice replacements for regular (soybean oil) mayo, though. They only have a little less sat fat (one gram per tablespoon, vs. two grams), and they're as high in total fat as the regulars.

Also not worth it are "cholesterol-free" mayos. A tablespoon of a full-fat mayo only has 5 mg of cholesterol, which is just a drop in the 300 mg daily maximum that most health authorities have set (or even our 200 mg limit).

Cutting the Mustard

Mustard is the perfect condiment. Strong-flavored and pungent, yet low in fat and sodium...as long as you use just a teaspoon at a time.

The only mustard that can get you in trouble is Hellmann's Dijonnaise.

Dijonnaise--despite its label's effort to hide the fact--is a mustard-mayonnaise mixture. It's got as much fat as a reduced-fat mayo. That's good if you're using it in place of mayo, not mustard.

Playing Ketchup

What could be bad about tomato concentrate or paste combined with a little sugar, vinegar, and flavorings? Nothing. It's the company ketchup keeps--greasy burgers and fries--that's the problem.

Ketchup averages two to three times the sodium of mustard. But that's only because people use three times as much of it (a tablespoon vs. a teaspoon) at a pop.

Salsa-sational

It means "sauce" in Spanish. And is it ever good.

Salsa's chopped tomatoes, peppers, onions, and spices have no added oil or (for most brands) sugar. Sodium can be a problem, but it's getting easier to find lower-sodium brands. Our favorites are Guiltless Gourmet Picante (Spanish for "spicy") and Newman's Own Bandito.

If your salsa experience stops at the end of a bag of tortilla chips, here are a few suggestions: Spoon it over a baked potato, omelette, salad, or plate of pasta or steamed veggies; stir it into a soup or stew.

B-B-King

Six out of every ten U.S. homes have a bottle of BBQ sauce in the refrigerator. And we bet that five of every ten don't have a clue that the sauce is probably loaded with salt.

Check the chart for those that aren't. If you can't find our three "Best Bites," try salsa or liquid smoke.

Soy, What's New?

Soy sauce is salty, all right. A tablespoon can set you back anywhere from 500 mg to more than 2,000 mg. So go easy.

And don't fall for sneaky Kikkoman and San-J's "low-sodium" claims. When the FDA's new labeling regulations take effect next year, they'll have to use a one-tablespoon serving, not the miserly half-teaspoon they now use. When that happens, "low-sodium" soy sauces will disappear.

Condillaneous

There's more to condiments than ketchup and mayo.

* Worcestershire sauce. A blend of vinegar, sweeteners, anchovies or sardines (vegetarians take note), salt, garlic, and hot peppers. Try it as a low-sodium substitute for steak sauce.

That Zincing Feeling

Q: In your article on prostate cancer (Cover Story, March 1993), you didn't mention whether taking zinc has any benefit. Does it?

--Robert M. Balkam Alexandria, Virginia

Dr.T: No, despite its popularity as a home remedy.

There is no scientific evidence that zinc is useful in treating either cancer or enlargement of the prostate, says John McConnell, who is an associate professor of urology at the University of Texas Southwestern Medical Center at Dallas.

Zinc earns another zero when it comes to treating prostate infections, adds McConnell. Even though the trace element is an important component of prostatic fluid, which helps fight infections, clinical tests have shown that "you can consume all the zinc you want and it's not going to change the amount of zinc in your prostatic fluid."

Bad Yolks

Q: I understand that the yolk of an egg has lots of cholesterol. Is most of it the "good" (HDL) or the "bad" (LDL) kind?

--Ken Fowler Fair Oaks, California 

Dr.T: There is no "good" or "bad" cholesterol in food. It's all lousy.

It's only after the cholesterol enters your bloodstream that it can attach itself to one of two types of protein-and-fat globs: "good" high-density lipoproteins (HDL) or "bad" low-density lipoproteins (LDL).

Odds are the cholesterol in your HDL ends up in your liver, where it is metabolized and eventually eliminated. LDL's cholesterol, on the other hand, often gets deposited in the walls of your arteries.

In other words: the more HDL in your blood (and the less LDL), the better.

Now here's the food connection: When you eat foods that are high in cholesterol (or saturated fat), you end up with more LDL in your blood.

Unfortunately, you can't raise your HDL through diet. The three best ways are to lose weight, exercise more, and quit smoking.

Mono & Di

Q: The label on Pepperidge Farm Soft Whole Wheat Bread says "fat free," yet the ingredient list contains "mono and diglycerides (from hydrogenated vegetable oil)." What does this mean?

--Lorraine M. Aubrey Bethlehem, Pennsylvania

Dr.T: Mono and diglycerides are fats, but a serving of your bread has less than a half-gram of them.

The FDA lets companies round their fat numbers to the nearest gram. And when you're talking about less than a half-gram, the nearest gram is zero. Hence the "fat free" on the label.

We wouldn't worry about such a tiny amount of mono & di. They almost never turn up in quantities that would add anything but a trivial amount of fat.

They're used, among other things, to make breads softer and prevent them from becoming stale, to improve the taste of margarine, and to prevent the oil in peanut butter from separating.